For example, a hydraulic excavator is equipped with an engine room (2) in the rear of its upper turning body (1), and an engine (3) and a hydraulic pump (4) driven thereby are provided in the engine room (2) as shown in FIGS. 25, 26.
In the opposite side of the hydraulic pump (4), there are installed a plurality of heat exchangers (5) such as a radiator for cooling the engine, an oil cooler, an intercooler, and the like (herein shown as one unit), and a cooling fan (6) driven by the engine (3); as the cooling fan (6) is rotated, as shown by an arrow in the attached figures, air sucked from the outside into the engine room (2) is passed through the heat exchanger (5) and discharged from an exhaust port (not shown).
The engine room (2) is formed by being enclosed with a cover member (7), utilizing a panel member called as an engine guard, a portion of a counterweight, a top face of a fuel tank, or the like and an air intake port (8) is provided in the cover member (7).
The air intake port (8) is formed in a side face (the face opposing the heat exchanger (5)) or in a top face of the cover member (7) on the side where the heat exchanger (5) is located. In FIG. 25, reference numeral (9) denotes a cabin.
This structure, however, has a problem of low soundproof performance, since any measures against air intake noise such as fan rotation noise, fan wind noise, suction noise of the heat exchanger, and the like have not been taken, and consequently most of the noise leaks outside directly through the air intake port (8).
As measures for overcoming the problem, as disclosed in Patent Document 1, an art is proposed in which a cooling air passage is arranged in an angular U-shaped configuration in plan view by extending the air intake space of an engine room toward the front of a machine, and an air intake port is provided at an end face of the air passage, the end face being oriented toward the center of the machine.
Patent Document 1: Japanese Unexamined Patent Application Publication No. H08-218869